Hemichorea associated with ipsilateral basal ganglia lesions.

Background: Hemichorea-hemiballism (HCHB) is a rare movement disorder typically associated with contralateral subthalamic nucleus (STN) lesions, but it may also occur ipsilaterally. This case report highlights a rare instance of ipsilateral HCHB caused by a putaminal hematoma, providing insights into its pathophysiology and management.

Case report: A 52-year-old female with a history of bioprosthetic valve replacement and hypertension presented with involuntary movements in the left arm. Neurological examination revealed choreiform movements in the right upper extremity and left hemihypoesthesia. Cranial CT showed a right putaminal hematoma, while MRI revealed no additional findings. Despite no response to a 7-day course of haloperidol, the patient showed significant improvement with risperidone treatment, achieving complete resolution of symptoms within five months.

Conclusion: HCHB is commonly associated with contralateral basal ganglia lesions; however, this case demonstrates its occurrence ipsilaterally, likely due to vascular disinhibition of basal ganglia structures. Antidopaminergic therapy, including risperidone, proved effective in managing the disorder. This report underscores the importance of recognizing ipsilateral HCHB as a rare but treatable clinical presentation.